Vol. 58. | GLACIER-LAKES IN THE CLEVELAND HILLS. 483 
A retreat from the upstream segment of a marginal overflow 
will produce a ‘ lateral intake.’ 
The other kind of serial development I have termed a parallel 
or successive sequence. These series, which frequently have 
also an alignment, consist of repeated trenchings of the same 
spur by parallel overflows. They are produced by an intermittent 
retreat of the ice-front, uncovering successively lower slopes of a 
hillside. It is satisfactory in These cases to find that the level at 
which each overflow commences to be cut is below the intake-level 
of its antecedent. This is beautifully illustrated by the interesting 
little pair of valleys on Moorsholm Rigg which I have termed ‘ the 
Double,’ and even better by the splendid series cutting the hills 
above Hayburn Wike. 
Sometimes a parallel sequence may be observed, in which the fall 
of the channels is in opposite directions in successive valleys of the 
sequence. ‘This is found in cases where there are two main over- 
flows at opposite ends of an aligned sequence, or where ice-streams 
‘from opposite quarters have successively invaded an area. 
The clearest case of the latter kind known to me, I observed in 
the Cheviots between the valley of the Breamish and Roddam Dean ' 
but in Cleveland the former phenomenon is to be well seen near 
Stanghow, and in a most perplexing development between two main 
escapes north and south of Scarborough. 
(4) In-and-out channels.—These are crescentic valleys 
excavated in the face of a hill by water flowing round a projecting 
lobe of ice. Two admirable examples are known to me in Cleveland, 
one detaching the hill known as Stony Ruck near Freeborough, 
and the other the Sunny Brake Valley near Glaisdale (see 
fig. 20, p. 530). 
I may now consider some peculiarities of form displayed by these 
valleys. 
The first Sevine that strikes the observer is their entire inde- 
pendence of the natural drainage. They cut across the natural 
watersheds, and frequently are deepest just where they pass through 
it. This feature it is which appears most decisively to point, not 
merely to obstructed drainage, but actually to the existence of 
bodies of standing water. 
The fall of these overflow-valleys is usually very small near the 
head and steepens rapidly down stream, a feature which is rarely 
observed in normal valleys. The small fall in the upper parts of 
these channels usually results in the accumulation of peat (to the 
depth, in some instances, of more than 20 feet), and this produces 
often a drainage out at the top end which obscures the character- 
istics of the intake. 
The transverse sections of the overflow-valleys are very cha- 
racteristic: they invariably exhibit exceedingly steep sides, and, 
1 P, F. Kendall & H, B. Muff, Geol. Mag. 1901, p. 513. 
